Based on the IHC results, we could exclude the high possibility of the following locations of the primary tumor: lung cancer (markers NAPSA−, TTF1−, P63−, synaptophysin/SYP−; Figure 5E),58, 59 gastrointestinal cancer (VIL1/Villin−; Figure 5F),60 prostate cancer (KLK3/PAS−; Figure 5G),61 and liver cancer (GPC−; Figure 5H).62 Here, SYP is linked to lung cancer.